Bluetooth speaker stops working after few minutes

[Klaus Eggert]

The bluetooth speaker is paired, trusted and connected via desktop controls. After some time the sound is aborted.

I'm using a clean raspbian stretch desktop image, default configs, ssh and vnc are enabled.
I enter the stream address in the internet browser. The sound starts.
After some time seconds, minutes or hours (last time it was 15min), the speaker is silent but remains connected.

model: RPi 3B
display: none (via vnc)
audio: bluetooth speaker JBL GO (20cm distance to the Raspi)
os: 2017-11-29-raspbian-stretch.img
internet connection via internal WLAN (1m distance to the router)
RealVNC to Win7 notebook
ssh to Win7 notebook
test stream: http://st01.dlf.de/dlf/01/128/mp3/stream.mp3

uname -a
Linux raspberrypi 4.9.59-v7+ #1047 SMP Sun Oct 29 12:19:23 GMT 2017 armv7l GNU/Linux

journalctl:
Dec 03 20:14:01 raspberrypi systemd[1]: Starting Cleanup of Temporary Directories...
Dec 03 20:14:01 raspberrypi systemd[1]: Started Cleanup of Temporary Directories.
Dec 03 20:16:22 raspberrypi bluealsa[505]: /usr/bin/bluealsa: BT socket write error: Resource temporarily unavailable

bluetoothctl:
[JBL GO]# info <device mac>
Device <device mac>
Name: JBL GO
Alias: JBL GO
Class: 0x240404
Icon: audio-card
Paired: yes
Trusted: yes
Blocked: no
Connected: yes
...

[Klaus Eggert (klaus-eggert)]

Today another test with a LAN connection between RPi 3B and the router. This time the sound aborts after 33min.

shell script to generated log.txt:

#!/bin/sh
LOG=log.txt
rm -f $LOG
date > $LOG
echo "---------------------------------" >> $LOG
echo "uname -a" >> $LOG
echo "- - - - - - - - - - - - - - - - -" >> $LOG
uname -a >> $LOG 2>&1
echo "---------------------------------" >> $LOG
echo "service bluetooth status" >> $LOG
echo "- - - - - - - - - - - - - - - - -" >> $LOG
sudo service bluetooth status >> $LOG 2>&1
echo "---------------------------------" >> $LOG
echo "service bluealsa status" >> $LOG
echo "- - - - - - - - - - - - - - - - -" >> $LOG
sudo service bluealsa status >> $LOG 2>&1
echo "---------------------------------" >> $LOG
echo "hciconfig -a" >> $LOG
echo "- - - - - - - - - - - - - - - - -" >> $LOG
sudo hciconfig -a >> $LOG 2>&1
echo "---------------------------------" >> $LOG
echo "strace -e trace=open,close,connect,accept bluetoothd -n" >> $LOG
echo "- - - - - - - - - - - - - - - - -" >> $LOG
sudo strace -e trace=open,close,connect,accept bluetoothd -n >> $LOG 2>&1
echo "---------------------------------" >> $LOG